(E2,Z6)-2,6-nonadienal is known as a useful intermediate for preparing (E2)-cis-6,7-epoxy-2-nonenal which is an aggregation pheromone of red-necked longhorn beetle (scientific name: Aromia bungii) known as a pest against Rosaceae trees such as cherry, Japanese apricot, peach, and plum (Non-Patent Literature 1 mentioned below). There is a need to establish an industrial and economical process for preparing the aforesaid intermediate, (E2,Z6)-2,6-nonadienal, in order to develop a new technology for preventing red-necked longhorn beetle, using an aggregation pheromone of the red-necked longhorn beetle.
The following processes have been reported to prepare (E2,Z6)-2,6-nonadienal: a process comprising ethylating and diethoxymethylating the two alkyne-ends, respectively, of 1,5-hexadiyne as a starting material, followed by partial hydrogenation (Non-Patent Literature 1, as mentioned below); a process starting with 4-pyranoxybutanal where a Wittig reaction is carried out twice (Non-Patent Literature 2, as mentioned below); a process of reacting (1,3-dioxolan-2-ylmethyl)triphenylphosphonium bromide with a base, followed by a Wittig reaction with Z-4-heptanal (Non-Patent Literature 3, as mentioned below); and a process of subjecting Z, Z, Z-1, 4, 7-cyclononatriene to ozonolysis (Non-Patent Literature 4, as mentioned below).